Mining is known for its long-lasting and resource consuming processes
which ultimately lead to an increase in cost and consumption of energy. For
instance, the Comminution process, the combination of grinding and crushing,
consumes approximately 3% of the total global electricity. In addition, the Coalition
for Energy Efficient Comminution (CEEC) states that the process is responsible
for 10% production costs.
Designs
In order to control the energy consumption, different
comminution circuit designs undergo a hit and trial approach since there is no
standard design that fits every circuit. Samples of the ore are collected and
their characteristics are studied comprehensively. The results of this analysis
are processed through various comminution designs until the energy savings are
maximized.
Circuit designers
Designers have to choose the appropriate type of mill (solid
material crushing device) or design depending upon the characteristics of ore,
applications, operation size, site location, environmental (natural factors), and
all round company requirements. For high moisture applications, the design is
made to suit autogenous or semi autogenous grinding. Similarly, in case of
solid rock applications, designers prefer a High-Pressure Grinding Roll (HPGR)
circuit since crushing is of upstream nature.
Equipment size and energy saving
Since the last three decades, the underlying notion
associated with energy saving has promoted the use of big machinery. However,
this cannot be considered as a universal choice for sites. Reduction ratio of comminution
machinery is directly and inversely proportional to the size and energy
conservation respectively.
Designers often encounter the dilemma of one large mill or
two small ones. While former supports cost reduction due to less equipment,
manpower, space, and material, latter ensures output even if one of the mills encounters
a functioning issue. Weighing the pros and cons, the concept of large mill was
preferred and consequently, semi autogenous grinding gained traction. However, it
wasn’t until a few years ago that F80 to P80 comminution machinery offered the
benefits of both mill arrangements in one system.
This made designers assume that energy saving is not necessarily
about reducing the number of grinding steps in every situation. It might be
possible that the steps may increase by one, but their concise nature can prove
instrumental in increasing energy conservation.
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